This invention relates to apparatus and method for connecting chains, cables and the like typically used to moor vessels offshore, such as mobile offshore drilling units (MODUs), floating production vessels, or other similar vessels. A typical mooring installation has the vessel secured to a plurality of anchors on or embedded in the seafloor, by flexible connecting members such as chains, cables, synthetic lines, or some combination thereof. For purposes of this application, all such flexible connecting members will be referred to as “chains” or “lines.”
Sections of line may be joined by members commonly known as “connecting links,” as is well known in the art. FIG. 1 shows an exemplary prior art connecting link 100. Connecting link 100 may be disassembled, the links of two other connectors or lines hooked into connecting link 100, then when connecting link 100 is reassembled it joins the two lengths of line. Primary parts of connecting link 100 are a generally C-shaped main body 102, a pair of mating caps 104 and 106, a link pin 108, and a retaining plug 110. As seen in FIG. 1, an opening O exists between the separated ends or ears 114 of main body 102. As is well known in the art, caps 104 and 106 fit together around main body 102, in particular having internal profiles 120 which mesh with the profiles 112 on the open ears 114, proximal opening O. Link pin 108 is then inserted through a hole 105 created by meshed caps 104 and 106, through holes 104A and 106A in overlapping members within meshed caps 104 and 106 (thus holding the caps together), and then into a hole 116 in connecting link 100, thus holding the caps together, and retaining the caps on connecting link 100. Hole 116 typically runs completely through main body 102, to emerge in a lower end of hole 116 at the bottom of main body 102.
A protrusion 107 on one of the caps, e.g. cap 106, typically fits into a key slot 109 in main body 102. Typically, a retaining plug 110 is then inserted on top of link pin 108 and within a cavity 118 at the uppermost section of the hole 105 formed by the meshed caps 104 and 106. Retaining plug 110 may be made of a soft metal such as lead, and may be simply hammered in place or preferably melted and cast in place, for improved retention. These methods and apparatus (i.e. the structure of the connecting link and how it is assembled) are all known in the art.
As can be understood by this description, the integrity of the connecting link assembly is dependent upon link pin 108 remaining in place and holding caps 104 and 106 in place on main body 102. Link pin 108 is typically simply a tapered pin (not threadably engaged), for ease of disassembly of connecting link 100. The open, lower end of hole 116 enables link pin 108 to be driven out from the bottom of main body 102, among other uses. While friction forces may be enough to hold link pin 108 in place, retaining plug 110 is important to ensure that link pin 108 remains in place.
An issue arises if retaining plug 110 comes out, and link pin 108 then begins to move out of its proper position. This situation might be revealed during underwater inspections of mooring assemblies, carried out by Remotely Operated Vehicles (ROVs), as is known in the art. If that happens, there is no known prior art apparatus and/or method by which link pin 108 can be pushed back into proper position, and retained in its proper position, which can be deployed and implemented subsea by an ROV.